Steerable Acid Tunneling System

ABSTRACT

Systems and methods for acid tunneling within a wellbore include a whipstock and a steerable acid tunneling arrangement which is run into the wellbore. The acid tunneling arrangement is azimuthally and angularly oriented by the whipstock. Information relating to the direction of tunnel development is sensed and provided to a controller at surface and can be used to map the tunnel.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates generally to systems and methods for creatinglateral tunnels within and stimulating subterranean formationssurrounding wellbores.

2. Description of the Related Art

Acid tunneling is a method of forming tunnels within a subterraneanformation using acid injection. Tools which are used currently for acidtunneling typically have a bottom hole assembly which features a wandhaving an acid-injection nozzle. The wand is connected to a base portionby a pair of flexible joints. These tools use increased fluid pressurepumped from surface to flex the joints of the tool, thereby changing theangle of the wand of the tool and influence the direction of the tunnelbeing created by acid injection. The tunnels which are created oftenundesirably curve or arc in an upward fashion through the formation dueto the upward movement and force of the wand from to pressure increaseswhich cause joint flexure during tunneling. Oftentimes, indexing toolsare used to rotate the acid tunneling bottom hole assembly to try tohelp orient the acid-injection nozzle angularly within the wellboreprior to flexing the tool joints. As acid is injected, a tunnel isformed in the formation which extends radially away from the mainwellbore.

The inventors have recognized that with many conventional acid tunnelingtool designs, it can be difficult or impossible to positively controlthe direction of tunnel development. The wand can become oriented in anumber of different directions given the variability of angular bendingand the dependence of flexure on fluid pressure from the surface.Improper orientation of the wand at the beginning stage of tunnelcreation can result in the tunnel being developed in a differentdirection than is desired. Indeed, the inventors believe that with mostconventional acid injection tool, the direction of tunnel development issubstantially random. Also, small changes in the directions of flexureor variations in formation material could undesirably create a crookedtunnel which could potentially cause the acid tunneling tool couldbecome stuck in rock and difficult to remove from the wellbore. Further,the inventors have recognized that, currently, there is no practical wayto verify the direction and angle of bend for the wand during operation.

SUMMARY OF THE INVENTION

The invention provides acid tunneling systems and methods for acidtunneling having positive direction control, or steering, for thedevelopment of tunnels. A steerable acid tunneling system is describedwhich includes a running string with an affixed acid tunneling bottomhole assembly. The acid tunneling bottom hole assembly preferablyincludes an acid injection tool having a wand which is connected to abase portion with a single flexible joint. In an alternative embodiment,the acid injection tool does not have a flexible joint. One or morenozzles are located within the distal end of the wand to inject acid inan axial direction. The acid tunneling bottom hole assembly alsopreferably incorporates a data sub which is operably associated with oneor more sensors. In preferred embodiments, there are one or more sensorswhich can measure or detect the orientation of the wand, includingangular deviation and azimuth. Tube-wire or another power and dataconduit is preferably included within the running string to transmitdetected information to a controller at the surface. Other telemetrymeans, such as optical fiber, could also be used. Information obtainedby the sensors is preferably used to control operational aspects of theacid injection tool. The information is preferably also used to maptunnels as tunnels are being formed by creating three-dimensionalrepresentations of the tunnels within the formation. This featureprovided real-time monitoring capability for the direction of tunneldevelopment and potentially for the mapping of tunnels.

In certain embodiments, a caliper is incorporated within the bottom holeassembly to measure tunnel diameter and/or topology of tunnels. Thisallows the diameter and/or topology of tunnels being formed to bemeasured in real-time. An operator can then make corrective adjustmentsto the tunneling process, if needed, such as by increasing the diameterof portions of a tunnel being formed. Alternatively, a caliper may berun into the wellbore after tunneling has been created in order tomeasure the diameter of portions of a completed tunnel. The inventorshave found that use of a caliper is beneficial in that it allows anoperator to optimize acid concentration to create a smaller diametertunnel and not waste acid flowing away from the tunnel face.

In an exemplary method of operation, a whipstock is first run into andsecured within the wellbore. The whipstock is oriented in direction ofdesired tunnel formation. Thereafter, a steerable acid tunneling systemis run into the wellbore. The wand of the acid tunneling tool isangularly (i.e., azimuth) oriented within the wellbore by the landingsurface of the whipstock. Additionally, the slope of the whipstocklanding surface will also dictate the initial orientation of the wand ofthe acid tunneling tool. Injection of acid will then develop a tunnel ina predetermined direction, as dictated by the whipstock.

In certain embodiments, a pulsating tool is incorporated into the bottomhole assembly. The pulsating tool can help create larger tunnels andincrease acid reaction efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

For a thorough understanding of the present invention, reference is madeto the following detailed description of the preferred embodiments,taken in conjunction with the accompanying drawings, wherein likereference numerals designate like or similar elements throughout theseveral figures of the drawings and wherein:

FIG. 1 is a side, cross-sectional view of an exemplary wellborecontaining a whipstock.

FIG. 2 is an axial cross-section taken along lines 2-2 in FIG. 1.

FIG. 3 is a side, cross-sectional view of the wellbore shown in FIGS.1-2, now with a steerable acid tunneling arrangement in accordance withthe present invention being run in.

FIG. 4 is a side, cross-sectional view of the wellbore shown in FIGS.1-3, now with acid tunneling being conducted.

FIG. 5 is a side, cross-sectional view of the wellbore shown in FIGS.1-4, now at a later stage of acid tunneling.

FIG. 6 is a side, cross-sectional view of the wellbore shown in FIGS.1-5, at a still later stage of acid tunneling.

FIG. 7 is a side, cross-sectional view of a portion of tunnelillustrating a technique for diametrically enlarging a tunnel beingformed.

FIG. 8 is a diagram illustrating an exemplary method for conducting acidtunneling in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates an exemplary wellbore 10 that has been drilledthrough the earth 12 from the surface 14 down to a hydrocarbon-bearingformation 16. It is noted that, while wellbore 10 is illustrated as asubstantially vertical wellbore, it might, in practice, have portionsthat are inclined or horizontally-oriented. A portion of the wellbore 10could be lined with a metallic casing (not shown). However, the portionsof the wellbore 10 which are to be stimulated are preferably not linedwith metallic casing.

FIG. 1 illustrates a whipstock 18 which has been secured within thewellbore 10 with a packer element 20. The upper end of the whipstock 18presents an angled landing surface 22. The whipstock 18 is positionedwithin the wellbore 10 at a wellbore location (i.e., depth) wherein itis desired to form tunnels within the formation 16 surrounding thewellbore 10. The angled landing surface 22 has an upper end 24 and alower end 26 and forms an acute angle (a) with respect to the axis ofthe wellbore 10 (or vertical) which is preferably from about 3 degreesto about 30 degrees. This angle α will largely dictate the initial angleof formation for a tunnel which is developed into the formation 16. Thesame schematics could be applied to horizontal or deviated wellbores.However, the angle α and tunnel direction will depend on the wellboremain axis and gravity direction.

FIGS. 1 and 2 illustrate azimuthal directions (N, S, E, W) from thewellbore 10. The landing surface 22 is directed in the radial direction(azimuth) wherein it is desired to form a tunnel. It is noted that inFIGS. 1-2, the landing surface 22 is oriented to face due east (E) sothat the direction of tunnel development from the wellbore 10 into theformation 16 will be toward the east. It should be noted that the eastdirection is exemplary only and that any azimuthal direction may bechosen.

FIG. 3 illustrates a steerable acid tunneling arrangement 30 now beingrun into the wellbore 10 from the surface 14. The acid tunnelingarrangement 30 includes a running string 32 which is preferably made upof coiled tubing. A flowbore 34 is defined along the length of therunning string 32.

An acid tunneling bottom hole assembly 36 is affixed to the distal endof the running string 32. The acid tunneling bottom hole assembly 36includes an acid tunneling tool 38 which is used to flow acid which ispumped from surface 14 into the formation 16. The acid tunneling tool 38includes a cylindrical base portion 40 and an acid injection wand 42. Anarticulable joint 44 connects the base portion 40 and the injection wand42. Each of the first and second articulable joints 38, 40 allows theconnected members to be moved angularly with respect to one another. Thearticulable joint 44 may be constructed and operate in the same manneras those used in the StimTunnel™ acid placement tool which is availablecommercially from Baker Hughes, a GE company, LLC of Houston, Tex.Preferably, the acid injection wand 42 is provided with end nozzles 46for injection of acid into portions of the formation 16 surrounding thewellbore 10. This configuration is preferred for acid tunneling becausethe acid flow through the end nozzles 46 will be directed generally inthe direction of intended tunnel creation (i.e., the direction towardwhich the acid injection wand 42 is pointing.

The acid tunneling bottom hole assembly 36 also preferably includes acaliper 48 which is capable of measuring or detecting the diameter orshape or size of a borehole surrounding the bottom hole assembly 36. Thecaliper 48 includes at least one finger 50 which protrudes radiallyoutwardly from the caliper body 52 to make contact with the surroundingwall. Preferably, the caliper 48 is an imaging caliper which can providea real-time, detailed visual representation of the shape and topologyfeatures of a surrounding surface. A suitable caliper device for use inthis application is the Baker Hughes Imaging Caliper which is availablecommercially from Baker Hughes, a GE company, LLC of Houston, Tex.Information provided by the caliper 48 is useful to balance acidconcentration versus tunnel creation. For instance, it is usuallyunknown whether acid injected from an acid tunneling tool is dissolvingrock in front (i.e., distal end) of the tool, contributing to increasedtunnel length, or is flowing toward the back (i.e., proximal end) of thetool, contributing to tunnel width (diameter) only. Information providedby the caliper 48 could be used to improve the acid pumping rate andcoiled tubing tripping speed while creating tunnels. Incorporation ofthe caliper 48 into the acid tunneling bottom hole assembly 36 allowsoperators to obtain such tunnel data in real time and adjust theoperational parameters (i.e., acid pumping rate and coiled tubingtripping speed) on the fly. Also, this tunnel data could be used tocreate a database which includes identification of the tunnel(s) beingcreated, reservoir properties, acid strength, pumping rate(s), andtripping speed.

The acid tunneling bottom hole assembly 36 also preferably includes adata sub 54. The data sub 54 includes electronics storage or memory 56to receive and store information received from sensor(s) 58. The one ormore sensors 58 are preferably disposed upon the wand 42 of the acidtunneling tool 38 and are interconnected with the storage or memory 56by a data conduit 60. The one or more sensors 58 will preferably includean inclinometer which will detect or measure the inclination of the wand42 (with respect to vertical) within the wellbore 10. In addition, theone or more sensors 58 also preferably include a compass or azimuthmeasurement device which will identify the angular orientation of thewand 42 with respect to azimuthal directions (N, E, S, etc.).

A data communications conduit 62, such as tube-wire, is preferably usedto transmit the received information to a surface-based controller andstorage medium 64 from the data storage or memory 56. Telecoil® is apreferred arrangement for this application and is coiled tubing whichincorporates tube-wire that can transmit power and data. Tube-wire isavailable commercially from manufacturers such as Canada TechCorporation of Calgary, Canada. Conduit 62 is shown within the flowbore34 of the running string 32 and is operably interconnected with thecontroller/storage medium 64 at surface 14 as well as the caliper 48 anddata storage 56 within the acid tunneling bottom hole assembly 30.

The controller/storage medium 64 may be programmable, and preferablyincludes suitable programming to use mathematical modeling to determinethe location and orientation of the wand 42 within the wellbore 10.Suitable programming for this application includes CIRCA™ RT modelingsoftware for coiled tubing applications. CIRCA™ Tools software may beused for geometric setup of tool angle, and CIRCA™ software may be usedto model forces and pressures in coiled tubing. Each of these softwarepackages is available commercially from Baker Hughes, a GE company, LLCof Houston, Tex. When CIRCA™ RT is used for modeling, a current coiledtubing force analysis is extended to take into account thetri-dimensional tunnel length extension by considering the chemicalreaction between acid and formation rock and the mechanical erosion dueto the fluid jet from nozzle 46 within the tunnel 74. Informationprovided by sensor(s) 58 is thereby used to model or map the tunnel 74and other tunnels by generating and displaying a representation of thesetunnels within the formation 16.

It is currently preferred that articulable joints 66 be used between theacid tunneling tool 38, the caliper 48 and the data sub 54 componentswithin the acid tunneling bottom hole assembly 30. The use ofarticulable joints 66 between some or all of these adjacent componentswill aid disposal of the bottom hole assembly 30 into tunnels that arecreated by acid tunneling. However, articulable joints are not necessaryto operation of the acid tunneling bottom hole assembly 30 and,depending upon the angle of departure for the direction 72 of intendedtunnel development, may be omitted.

During acid tunneling, acid is flowed from an acid supply 68 at surface14 by pump 70 through the flow bore 22 of the running string 20 to thebottom hole assembly 26. The pump 70 is preferably a variable speed orvariable capacity pump.

In the depicted embodiment, the acid tunneling bottom hole assembly 30includes a pulsating tool 76 which is shown located between the caliper48 and the data sub 54. A suitable pulsating tool for use in thisapplication is an EasyReach Extended Reach Tool which is availablecommercially from Baker Hughes, a GE company, LLC of Houston, Tex. Thepulsating tool 76 uses water hammer effect to create pressure waveswithin acid that is pumped down to the acid tunneling tool 38 fromsurface 14.

Preferred methods of operation, are illustrated in FIGS. 1-6. Referringfirst to FIGS. 1 and 2, whipstock 18 is run into the wellbore 10 andretained at a desired depth or location by setting packer 20 within thewellbore 10. The landing face 22 of the whipstock 18 is oriented in adesired azimuthal direction (i.e., east, west, etc.). FIG. 3 shows thesteerable acid tunneling arrangement 30 being disposed within thewellbore 10. In FIG. 4, the wand 42 of the acid tunneling tool 38contacts the landing surface 22 of the whipstock 18 and is deflected sothat the end nozzles 46 of the wand 42 are oriented to inject acid intothe formation 16 in an initial desired tunneling direction 72 which isdetermined by the azimuthal orientation of the landing surface (i.e.,toward the east) and the angle of the landing surface 22 with respect tothe vertical. Therefore, the wand 42 and direction of acid tunneling issteered by the initial selection and orientation of the landing surface22 of the whipstock 18.

To begin tunneling, acid is then flowed by the pump 70 from the acidsupply 68 to the acid tunneling tool 38 in order to exit the end nozzle42, as illustrated in FIG. 4. As acid is pumped, a lateral tunnel 74begins to form. Injected acid interacts with the rock within theformation 16, creating tunnel 74 that increases reservoir conductivity.The shape, direction and length of the tunnel 74 depends on tool lengthand inclination angles, the nozzle 46 properties (shape, number, etc.),the coiled tubing yield radius, and the acid/rock interaction (type ofacid and rock, pumping rate, etc.).

FIG. 5 shows a subsequent time during tunneling wherein the length ofthe lateral tunnel 74 has advanced. The wand 42 and then a significantportion of the remainder of the acid tunneling bottom hole assembly 30have now entered the lateral tunnel 74. During tunneling, sensor(s) 58detect inclination of the wand 42 and signals indicative of this aresent to the controller 64 at surface 14. FIG. 6 illustrates a subsequenttime wherein acid tunneling has substantially been completed. At thispoint, the entire acid tunneling bottom hole assembly 30 is locatedwithin the lateral tunnel 74. The caliper 48 can measure the diameterand topological features of the lateral tunnel 74. The acid tunnelingarrangement 30 provides real-time information to the controller 64 atsurface 14 regarding the direction of tunnel 74 development as well astunnel 74 diameter and topology features.

In order to form the lateral tunnel 74, at least some portion of theprocess of forming tunnel 74 within the formation 16 is preferablycontrolled based upon information sensed by the sensor(s) 58 relating tothe angular and azimuthal orientation of the wand 42. Data sent to thecontroller 64 at surface 14 is used to control the acid tunneling tool38. For example, acid flow to the acid tunneling tool 38 may beincreased by the pump 70 and/or actuation of the pulsating tool 76 toincrease tunnel length. Alternatively, if the caliper 48 detects thatthe diameter of the tunnel 74 being created is too small, then thenature of the acid being used or its flow rate or the location of thewand 42 within the tunnel 74 may be altered to cause the tunnel 74diameter to be increased.

One method of increasing diameter of the tunnel 74 is to increase theacid concentration while continuing to create new tunnel length (i.e.,acid injection). Only so much acid is used to react against theformation 16 prior to being displaced back toward the wellbore 10. Anoperator could then displace formation 16 material at the same pump ratebut with a higher acid concentration leaving more acid available toreact on the smaller tunnel 74 and increasing its diameter.

An alternative method of increasing tunnel diameter is illustrated inFIG. 7, the nozzle 46 could be pulled back a short distance 78 (say onefoot or so) from the distal end 80 of the tunnel 74 during tunneling sothat little or no acid jetting is occurring at the distal end 80 therebyallowing a greater concentration of acid proximate the nozzle 46 and alesser concentration near the distal tunnel end 80 causing the tunnel 74to be enlarged radially (see 82) proximate the nozzle 46. FIG. 7 depictsthe initial position of the acid tunneling tool 38 in phantom lines andthe pulled-back position in solid lines.

In order to optimize tunneling processes, most if not all, injected acidshould be used to extend the tunnel length. If too much acid is pumpedtoo fast, some of it will not have time to react with the formation 16rock at the distal tunnel end 80 and it will flow back towards the mainwellbore 10. There it could uncontrollably enlarge the tunnel and/orcreate wormholes without knowing how much acid is used to extend thetunnel lengths and how much acid is increasing tunnel diameter. Tunnellength can be optimized by determining and pumping an amount of acidthat is sufficient to extend tunnel length without wasting excess acidwhich would diametrically enlarge the tunnel 74. By using real-timetelemetry, software modeling and a caliper 48, the pumped acid volumecan be optimized to reduce job cost and logistics.

Directional control and steering for the acid tunneling bottom holeassembly 30 are primarily achieved by virtue of the whipstock 18 and itsangled landing surface 22. Once the acid tunneling bottom hole assembly30, and primarily the wand 42, become oriented in the desired tunnelingdirection 72, acid injection will continue to develop the tunnel 74 inthat desired direction 72. The procedure of simultaneously jetting acid(via nozzle 46) and pushing force upon the bottom hole assembly 30 inthe desired direction 72 extends the length of the lateral tunnel 74 inthe desired direction 72. In contrast to tunneling techniques which haveformed curved or arched tunnels, tunnels created using the systems andmethods of the present invention tend to be substantially linear orstraight rather than curved.

The direction of tunnel creation and the dimensions of the tunnel beingcreated can be monitored in real-time as the lateral tunnel 74 isdeveloped. As a result, operators at surface 14 can developthree-dimensional maps or representations which include the shape,direction and topological features of lateral tunnel 74 and othertunnels which are developed using the systems and methods of the presentinvention.

It should be understood that the invention provides systems forconducting acid tunneling within a wellbore. An exemplary systemincludes a whipstock 18 having an angled landing surface 22, thewhipstock 18 being secured within a wellbore 10. The system would alsoinclude a steerable acid tunneling arrangement 30 which has an acidtunneling tool 38 that is azimuthally oriented within the wellbore 10 bythe whipstock landing surface 22. The acid tunneling tool 38 has a wand42 which presents a nozzle 46 to inject acid in the desired tunnelingdirection 72, and the wand 42 is angularly oriented (with respect tovertical) by the landing surface 22 of the whipstock 18. Sensor(s) 58are associated with the wand 42 to detect angular inclination andazimuthal direction of the wand 42 which is indicative of the directionof tunnel 74 development. The sensor(s) 58 provided a signal indicativeof the sensed information to the controller 64 at surface 14. Inparticular embodiments, the acid tunneling tool 38 is included within anacid tunneling bottom hole assembly 30 which also includes a caliper 48which is configured to measure the diameter and/or topology of thetunnel 74. Also in particular embodiments, the acid tunneling bottomhole assembly 30 includes pulsating tool 76. The pulsating tool 76 willtemporarily and intermittently restrict flow of acid which is flowingtoward the acid tunneling tool 38 to create pressure pulses which couldminimize the acid volume further. For pressure peaks developed by thepulsating tool 76, the acid flow rate, and so that acid volume, can bereduced to obtain essentially the same pressures as with higher acidflow rates used without a pulsating tool. In preferred embodiments, tubewire is used to transmit detected information about tunnel directionand/or diameter and/or topology to a controller 64 at surface 14.

Additionally, the invention provides methods for acid tunneling whereina whipstock 18 is first secured within a wellbore 10, the whipstock 18presenting an angled landing surface 22. Thereafter, an acid tunnelingarrangement 30 having an acid tunneling tool 38 is run into the wellbore10. The acid tunneling tool 38 contacts the whipstock 18 and the landingsurface 22 azimuthally orients the acid tunneling tool 38. The landingsurface 22 of the whipstock 18 also angularly orients a wand 42 of theacid tunneling tool 38 with respect to vertical as the wand 42 islowered further onto the landing surface 22. Acid is pumped through theacid tunneling tool 38 to inject acid in a desired tunneling directionand form a lateral tunnel 74. During tunneling, the angular inclinationand azimuthal direction of the wand 42 is detected by one or moresensors 58. The detected information is transmitted to a controller 64,and the information is used to steer the acid tunneling tool 38 and/orcreate a map or representation of the tunnel 74. In some embodiments,the information is used to create a map or representation of the tunnel74.

FIG. 8 depicts an exemplary method 84 for conducting acid tunnelingwithin a formation 16 which surrounds a wellbore 10. In step 86, an acidtunneling tool 38 is run into the wellbore 10. In step 88, the acidtunneling tool 38 contacts a landing surface 22 of the whipstock 18 andis steered or oriented azimuthally and angularly. Acid is injectedthrough the wand 42 of the acid tunneling tool 38 to create a tunnel 74which is developed in a desired tunneling direction 72 (step 90). Instep 92, angular and azimuthal orientation of the wand 42 are detectedby sensor(s) 58. In step 94, tunnel diameter and/or tunnel topology isdetected using the caliper 48. Tunnel diameter can be enlarged in step96 using techniques described previously. In step 98, acid pump rateand/or acid concentration are adjusted for maximize tunnel lengthcreation. In step 100, the lateral tunnel 74 is mapped or modeled by thecontroller 64 by creating a three-dimensional representation of thetunnel 74 within the formation 16.

What is claimed is:
 1. A system for conducting acid tunneling within awellbore, the system comprising: a whipstock having an angled landingsurface; an acid tunneling arrangement to be run into the wellbore andhaving an acid tunneling tool to direct acid injection in a desiredtunneling direction, the acid tunneling tool being azimuthally orientedwithin the wellbore by the whipstock landing surface as the acidtunneling tool is brought into contact with the landing surface; theacid tunneling tool having an acid injection wand to directs acid towardthe desired tunneling direction, the wand further being angularlyoriented with respect to a vertical by disposal upon the landingsurface.
 2. The system of claim 1 further comprising: a sensor operablyassociated with the wand to sense azimuth and/or orientation of thewand; and a controller operably associated with the sensor to receivefrom the sensor a signal indicative of the sensed information.
 3. Thesystem of claim 1 wherein: the acid tunneling tool is contained withinan acid tunneling bottom hole assembly; and the bottom hole assembly isaffixed to a running string for disposing the bottom hole assembly intothe wellbore.
 4. The system of claim 3 wherein the acid tunneling bottomhole assembly further comprises: a caliper which is configured to detecta diameter and/or topological information regarding a tunnel beingformed and provide a signal indicative of the detected information to acontroller.
 5. The system of claim 3 wherein the acid tunneling bottomhole assembly further comprises: a pulsating tool which creates pressurewaves within acid being pumped to the acid tunneling tool.
 6. The systemof claim 2 wherein the controller is operably associated with the sensorby tube wire.
 7. The system of claim 2 wherein the controller isoperable to map or model a tunnel created within a formation surroundingthe wellbore.
 8. A method for acid tunneling comprising: securing awhipstock within a wellbore, the whipstock presenting an angled landingsurface; disposing an acid tunneling arrangement into the wellbore, theacid tunneling arrangement having an acid tunneling tool with a wandhaving a nozzle to inject acid in a desired acid tunneling direction;contacting the angled landing surface with the acid tunneling tool toazimuthally orient the acid tunneling tool within the wellbore;angularly orienting the wand within the wellbore by further lowering theacid tunneling tool onto the landing surface; and forming a lateraltunnel from the wellbore by injecting acid through the wand.
 9. Themethod of claim 8 further comprising the step of detecting azimuthal andangular orientation of the wand with a sensor.
 10. The method of claim 8further comprising the step of detecting a diameter and/or topologicalinformation regarding the lateral tunnel with a caliper.
 11. The methodof claim 8 further comprising the step of creating a three-dimensionalrepresentation of the lateral tunnel to map or model the lateral tunnel.12. The method of claim 8 further comprising the step of radiallyenlarging a portion of the lateral tunnel by increasing acidconcentration within the injected acid.
 13. The method of claim 8further comprising the step of radially enlarging a portion of thelateral tunnel by: pulling the nozzle of the acid tunneling tool awayfrom a distal tunnel end; and injecting acid to cause radial enlargementof a portion of the wellbore proximate the nozzle.
 14. The method ofclaim 8 further comprising the step of adjusting acid concentrationand/or acid flow rate to optimize tunnel length creation.